SFI SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components of the 1KR-FE engine control system are as follows.

      Components Outline Quantity Function
      ECM 16-bit CPU 1 The ECM optimally controls the SFI, ESA, and ETCS-i to suit the operating conditions of the engine in accordance with the signals provided by the sensors.
      Crank Position Sensor (Rotor Teeth) Pick-up Coil Type (36-2) 1 This sensor detects the engine speed and performs cylinder identification.
      Cam Position Sensor (Rotor Teeth) Hall Type (3) 1 This sensor performs cylinder identification.
      Knock Control Sensor Built-in Piezoelectric Element Type (Flat Type) 1 This sensor detects an occurrence of the engine knocking indirectly from the vibration of the cylinder block caused by the occurrence of engine knocking.
      E.F.I. Vacuum Sensor Assembly Semiconductor Silicon Chip Type 1 This sensor uses built-in semiconductors to detect the intake manifold pressure.
      Intake Air Temperature Sensor Thermistor Type 1 This sensor is built into the E.F.I. vacuum sensor assembly.
      This sensor detects the intake air temperature by means of an internal thermistor.
      Throttle Position Sensor Non-contact Type 1 This sensor detects the throttle valve opening angle.
      Oxygen Sensor Planar Type with Heater 2 This sensor detects the oxygen concentration in the exhaust emission by measuring the electromotive force which is generated in the sensor itself.
      Accelerator Pedal Sensor Assembly Non-contact Type 1 This sensor detects the amount of pedal effort applied to the accelerator pedal.
      E.F.I. Engine Coolant Temperature Sensor Thermistor Type 1 This sensor detects the water temperature by means of an internal thermistor.
      Fuel Injector Assembly 4-hole Type 3 The fuel injector is an electromagnetically-operated solenoid with a nozzle which injects fuel in accordance with signals from the ECM.

  2. SYSTEM CONTROL


    1. The engine control system of the 1KR-FE engine has the following systems.

      Components Function
      Sequential multiport Fuel Injection (SFI) The D-type SFI system calculates the intake air volume based on the intake manifold pressure signal received from the E.F.I. vacuum sensor assembly and the engine speed.
      An independent injection system in which fuel is injected once into each cylinder for each two revolution of the crankshaft is used.
      Fuel injection takes two forms: Synchronous injection, which always takes place with the same timing in accordance with the basic injection duration and an additional correction based on the signals provided by the sensors. Non-synchronous injection, which takes place at the time an injection request based on the signals provided by the sensors is detected, regardless of the crankshaft position.
      Electronic Spark Advance (ESA) Ignition timing is determined by the ECM based on signals from various sensors. The ECM corrects ignition timing in response to engine knocking.
      This system selects the optimal ignition timing in accordance with the signals received from the sensors and sends the (IGT) ignition signal to the igniter.
      Electronic Throttle Control System-intelligent (ETCS-i) Optimally controls the throttle valve opening in accordance with the amount of accelerator pedal effort, the throttle valve opening control request from the ECM, and the condition of the engine and the vehicle.
      Variable Valve Timing-intelligent (VVT-i) Controls the intake camshaft to an optimal valve timing in accordance with the engine condition.
      Fuel Pump Control Fuel pump operation is controlled by signals from the ECM.
      A fuel cut control is used to stop the fuel pump when the airbag is deployed during front or side collision.
      Cooling Fan Control Cooling fan operation is controlled by signals from the ECM based on the E.F.I. engine coolant temperature sensor signal.
      Oxygen Sensor Heater Control Maintains the temperature of the heated oxygen sensor at an appropriate level to increase accuracy of detection of the oxygen concentration in the exhaust gas.
      Engine Immobiliser Prohibits fuel delivery and ignition if an attempt is made to start the engine with an invalid key.
      Air Conditioning Cut-off Control* By turning the air conditioning compressor on or off in accordance with engine operating conditions, drivability is maintained.

      • *: Models with air conditioning system

    2. Variable Valve Timing-intelligent (VVT-i) System


      1. The VVT-i system is designed to control the intake camshaft within a range of 45° (of Crankshaft Angle) to provide valve timing that is optimally suited to the engine condition. This improves torque in all the speed ranges as well as increasing fuel economy, and reducing exhaust emissions.

        A01UW10E02
        A01UVX3E02

      2. The VVT-i system delivers excellent benefit vehicle states as shown in the table below.

        Operation State Objective Effect
        During Idling A01UW0BE01
        *1 TDC
        *2 Latest Timing
        *3 BDC
        		Decreasing overlap to reduce blow back to the intake side.

        • Stabilized idling rpm

        • Better fuel economy
        At Light Load A01UVV9E01
        *1 to Retard Side
        		Decreasing overlap to reduce blow back to the intake side. Ensured engine stability
        At Medium Load A01UW60E01
        *1 to Advance Side
        		Increasing overlap to increase internal EGR to reduce pumping loss.

        • Better fuel economy

        • Improved emission control
        In Low to Medium Speed Range with Heavy Load A01UVV0E01
        *1 to Advance Side
        		Advancing the intake valve close timing for volumetric efficiency improvement. Improved torque in low to medium speed range
        In High Speed Range with Heavy Load A01UW1JE01
        *1 to Retard Side
        		Retarding the intake valve close timing for volumetric efficiency improvement. Improved output
        At Low Temperatures A01UVVME01
        *1 Latest Timing
        		Eliminating overlap to reduce blow back to the intake side leads to the lean burning condition, and stabilizes the idling speed at fast idle.

        • Stabilized fast idle rpm

        • Better fuel economy

        • Upon Starting

        • Stopping the Engine

        		 A01UWDQE01
        *1 Latest Timing
        		Eliminate overlap to reduce blow back to the intake side. Improved startability

    3. Fuel Pump Control


      1. In this system, the airbag deployment signal from the airbag sensor assembly is detected by the ECM, and it turns off the circuit opening relay. After the fuel cut control has been activated, turning the power source from off to on or selecting the ignition switch from off to on mode cancels the fuel cut control, and the engine can be restarted.

    4. Cooling Fan Control


      1. A cooling fan control system controlled to achieve an optimal fan speed in accordance with the engine coolant temperature, vehicle speed, engine speed, and air conditioning operating conditions.

  3. CONSTRUCTION


    1. ECM


      1. The ECM is installed in the engine compartment. As a result, the wiring harness has been shortened, thus realizing weight reduction.

        A01UWK4E02
        Text in Illustration
        *1 ECM - -

    2. Crank Position and Cam Position Sensors


      1. Pick-up coil type crank position sensor is used.

      2. The timing rotor of the crankshaft consists of 34 teeth, with 2 teeth missing. The crank position sensor outputs the crankshaft rotation signals every 10°, and the missing teeth are used to determine the top-dead-center.

      3. Hall type cam position sensor is used.

      4. To detect the camshaft position, a timing rotor on the intake camshaft is used to generate 3 pulses for every 2 revolutions of the crankshaft.

        A01UWQ8E02
        Text in Illustration
        *1 Crank Position Sensor *2 Crankshaft Timing Gear or Sprocket
        *3 Camshaft *4 Cam Position Sensor
        A01UVZ6E03
        Sensor Output Waveforms
        *a Cam Position Sensor
        *b Crank Position Sensor
        *c 2 Teeth Missing

      5. The Hall type cam position sensor consists of magnet and Hall IC. The distance between the pin on the timing rotor and the cam position sensor changes with the rotational movement of the timing rotor. As a result, the magnetic flux of the magnet inside the cam position sensor changes. The Hall IC transmits this change to the ECM in the form of output voltage. The ECM detects the cam position based on this output voltage.

      6. The differences between the MRE type sensor and the pick-up coil type sensor used on a conventional model are as follows.


        • An MRE type sensor outputs a constant level of Hi/Lo digital signals regardless of the engine speed. Therefore, an MRE type sensor can detect the positions of the crankshaft and camshaft at An early stage of cranking.

        • A pickup coil type sensor outputs analog signals with levels that change with engine speed.

        A01UWLGE17

    3. Camshaft Timing Oil Control Valve Assembly


      1. This camshaft timing oil control valve assembly controls the spool valve using duty-cycle control from the ECM. This allows hydraulic pressure to be applied to the VVT-i controller (camshaft timing sprocket assembly) advance or retard side. When the engine is stopped, the camshaft timing oil control valve assembly is in the most retarded position.

        A01UW4WE02
        Text in Illustration
        *1 Spring *2 Sleeve
        *3 Spool Valve - -
        *a To Intake VVT-i Controller (Camshaft Timing Sprocket Assembly) (Advance Side) *b To Intake VVT-i Controller (Camshaft Timing Sprocket Assembly) (Retard Side)
        *c Drain *d Oil Pressure

    4. Knock Control Sensor (Flat Type)


      1. In a conventional knock control sensor (resonant type), a vibration plate is built into the sensor. This plate has the same resonance point as the knocking frequency of the engine block. This sensor can only detect vibration in this frequency band.

      2. A flat type knock control sensor (non-resonant type) has the ability to detect vibration in a wider frequency band (from about 6 kHz to 15 kHz). It has the following features.

      3. The engine knocking frequency will vary slightly depending on the engine speed. The flat type knock control sensor can detect vibration even when the engine knocking frequency changes. Due to the use of the flat type knock control sensor, the vibration detection ability is increased compared to a conventional type knock control sensor, and more precise ignition timing control is possible.

        A01UWLNE26

      4. A flat type knock control sensor is installed to an engine by placing it over the stud bolt installed on the cylinder block sub-assembly. For this reason, a hole for the stud bolt exists in the center of the sensor.

      5. In the sensor, a steel weight is located in the upper portion. An insulator is located between the weight and a piezoelectric element.

      6. An open/short circuit detection resistor is integrated in the sensor. When the ignition is ON, the open/short circuit detection resistor in the knock control sensor and the resistor in the ECM keep the voltage at terminal KNK1 constant. An IC (Integrated Circuit) in the ECM constantly monitors the voltage of terminal KNK1. If the open/short circuit occurs between the knock control sensor and the ECM, the voltage of terminal KNK1 will change and the ECM will detect the open/short circuit and store a DTC.

        A01UWH3E08
        Text in Illustration
        *A Flat Type Knock Control Sensor (Non-Resonant Type) *B Conventional Type Knock Control Sensor (Resonant Type)
        *1 Steel Weight *2 Insulator
        *3 Piezoelectric Element *4 Open Circuit Detection Resistor
        *5 Vibration Plate - -
        A01UWKWE18
        *1 Flat Type Knock Control Sensor
        *2 Open/Short Circuit Detection Resistor
        *3 Piezoelectric Element

      7. Vibrations caused by knocking are transmitted to the steel weight. The inertia of this weight applies pressure to the piezoelectric element. This action generates electromotive force.

        A01UWNEE12
        Text in Illustration
        *1 Steel Weight *2 Piezoelectric Element
        A01UWJU Inertia - -

    5. E.F.I. Vacuum Sensor Assembly


      1. The E.F.I. vacuum sensor assembly has a built-in intake air temperature sensor.

      2. The E.F.I. vacuum sensor assembly consists of a silicon chip which utilizes the characteristic of a silicon chip that changes its electrical resistance when pressure is applied to it. The sensor converts the pressure into an electrical signal, and sends it to the ECM in an amplified form.

      3. The intake air temperature sensor detects the intake air temperature in the intake manifold via a thermistor.

        A01UWP5E02
        Text in Illustration
        *1 E.F.I. Vacuum Sensor Assembly *2 Silicon Chip
        *3 Thermistor - -
        A01UWBYE03

    6. Throttle Position Sensor


      1. The throttle position sensor is mounted on the throttle body to detect the opening angle of the throttle valve. The throttle position sensor converts the magnetic flux density that changes when the magnetic yoke (located on the same axis as the throttle shaft) rotates around the Hall IC into electric signals to operate the throttle control motor.

        A01UW8HE02
        Text in Illustration
        *1 Throttle Control Motor *2 Throttle Position Sensor
        *3 Throttle Valve - -
        A01UWHWE17

    7. Oxygen Sensor


      1. A planar type heated oxygen sensor is used.

      2. Compared to the conventional type (cup type), the sensor and heater portions of the planar type are narrower overall. Because the heat of the heater acts directly on the alumina and zirconia (of the sensor portion), it accelerates the activation of the sensor.

        A01UWFDE02
        Text in Illustration
        *1 Alumina *2 Atmosphere
        *3 Heater *4 Sensor Element (Zirconia)
        *5 Platinum Electrode - -

    8. Accelerator Pedal Sensor Assembly


      1. The non-contact type accelerator pedal sensor assembly uses a Hall IC.

      2. The magnetic yoke that is mounted at the accelerator pedal arm rotates around the Hall IC in accordance with the amount of effort that is applied to the accelerator pedal. The Hall IC converts the changes in the magnetic flux that occur at that time into electrical signals, and outputs them as accelerator pedal effort to the ECM.

      3. The Hall IC contains circuits for the main and sub signals. It converts the accelerator pedal depressed angles into electric signals with two differing characteristics and outputs them to the ECM.

        A01UVW8E05
        Text in Illustration
        *1 Magnetic Yoke *2 Accelerator Pedal Arm
        *3 Magnet *4 Hall IC
        *a Internal Construction *b A-A Cross Section
        A01UWFKE07

    9. No. 1 Ignition Coil


      1. An igniter is integrated with the ignition coils, which are provided independently in each cylinder. This improves ignition timing accuracy, reduces high-voltage loss and enhances the overall reliability of the ignition system by eliminating the distributor.

      2. The spark plug caps, which provide contact to spark plugs, are integrated with a No. 1 ignition coil. Also, an igniter is enclosed to simplify the system.

        A01UWQGE03
        Text in Illustration
        *1 Igniter *2 Iron Core
        *3 Spark Plug Cap *4 Secondary Coil
        *5 Primary Coil - -

    10. Spark Plug


      1. Long-reach type spark plugs are used. This type of spark plugs allows the area of the cylinder head to receive the spark plugs to be made thick. Thus, the water jacket can be extended near the combustion chamber, which contributes to cooling performance.

        A01UWGVE04
        Text in Illustration
        *a Long-reach Type *b Conventional Type
        *1 Water Jacket - -

  4. OPERATION


    1. VVT-i (Variable Valve Timing-intelligent) System


      1. Using the engine speed signal, vehicle speed signal, and the signals from E.F.I. vacuum sensor assembly, throttle position sensor and E.F.I. engine coolant temperature sensor, the ECM can calculate optimal valve timing for each driving condition and controls the camshaft timing oil control valve assembly. In addition, the ECM uses signals from the camshaft position sensor and the crank position sensor to detect the actual valve timing, thus providing feedback control to achieve the target valve timing.

        A01UVVDE06

      2. When the camshaft timing oil control valve assembly is operated as illustrated below by the advance signal from the ECM, the resultant oil pressure is applied to the timing advance side vane chamber to rotate the camshaft in the timing advance direction.

        A01UWBIE07
        *1 Vane
        *2 Oil Pressure
        *3 Drain
        *4 Rotation Direction

      3. When the camshaft timing oil control valve assembly is operated as illustrated below by the retard signal from the ECM, the resultant oil pressure is applied to the timing retard side vane chamber to rotate the camshaft in the timing retard direction.

        A01UVYTE06
        *1 Rotation Direction
        *2 Oil Pressure
        *3 Drain
        *4 Vane

      4. After reaching the target timing, the valve timing is held by keeping the camshaft timing oil control valve assembly in the neutral position unless the traveling state changes. This adjusts the valve timing at the desired target position and prevents the engine oil from running out when it is unnecessary.

    2. Fuel Pump Control


      1. The fuel pump control is used to stop the fuel pump when the airbags deploy in a front or side collision.

      2. In this system, when the airbag deployment signal from the airbag sensor assembly is detected by the ECM, the ECM turns off the circuit opening relay.

      3. After the fuel cut control has been activated, turning the ignition switch from off to ON cancels the fuel cut control, and the engine can be restarted.

        A01UVZIE05

    3. Cooling Fan Control


      1. According to the cooling fan drive request signal (low or high) from the air conditioning amplifier assembly and the engine coolant temperature, the ECM regulates the cooling fan speed over 2 levels. A cooling fan drive request signal is determined by the air conditioning amplifier assembly depending on mainly the refrigerant pressure and the A/C switch status.

      2. The low speed operation is accomplished by applying the current through a resistor, which reduces the speed of the cooling fan.

        A01UVYAE18
        Engine Coolant Temperature Cooling Fan Drive Request Signal Cooling Fan Operation
        Low Off Off
        Low Low
        High High
        High Off High
        Low High
        High High

  5. FAIL-SAFE


    1. When the ECM detects a malfunction, the ECM stops or controls the engine according to the data already stored in the memory. For details, refer to the Repair Manual.

  6. DIAGNOSIS


    1. When the ECM detects a malfunction, the ECM diagnoses and memorizes the failed section. For details, refer to the Repair Manual.